title: Spontaneous drinking: is it stimulated by hypertonicity or hypovolemia?
abstract: Ten young female pigs were allowed to eat and drink whenever they wanted, and blood samples were taken without disturbance to the pig. Samples were divided into four categories: 1) base line, i.e., taken when not drinking and not eating; 2) preprandial, i.e., taken when starting to drink just before eating; 3) postcibal, i.e., taken when starting to drink after any eating; and 4) nonprandial, i.e., taken when starting to drink but not in association with eating. Osmolality (mosmol/kgH2O), plasma protein (g/dl), and packed cell volume (%) were, respectively, as follows (mean +/- SE): base line 294.9 +/- 1.8, 6.2 +/- 0.1, and 30.0 +/- 1.2; preprandial 295.1 +/- 1.7, 6.1 +/- 0.2, and 29.7 +/- 1.4; postcibal 295.0 +/- 3.3, 6.5 +/- 0.2, and 31.7 +/- 1.3; and nonprandial 295.2 +/- 1.4, 6.3 +/- 0.1, and 30.0 +/- 1.3. None of the parameters associated with drinking were significantly different from base-line parameters, except for the postcibal rise of packed cell volume. Calculated blood volume differences from base line were as follows: preprandial 0.7 +/- 1.2% fall; postcibal 0.2 +/- 1.7% increase; and nonprandial 0.8 +/- 0.9% fall. It is unlikely that either plasma hypertonicity or hypovolemia stimulates drinking under spontaneous conditions.
authors.affiliation: Department of Physiology, New York State College of Veterinary Medicine, Cornell University, Ithaca 14853.
authors.forename: T R
authors.initials: TR
authors.lastname: Houpt
authors.forename: C R
authors.initials: CR
authors.lastname: Anderson
mesh_terms: D000818:Animals; D001769:Blood / Q000378:metabolism*; D001798:Blood Proteins / Q000032:analysis; D001810:Blood Volume; D004326:Drinking / Q000502:physiology*; D005260:Female; D005508:Food Deprivation / Q000502:physiology; D006400:Hematocrit; D009994:Osmolar Concentration; D014868:Water Deprivation / Q000502:physiology
chemical_list: D001798:Blood Proteins